[SanDiego78]

1978 CX500, 4700 miles, inherited from my father. I believe I have determined the stator is bad. Bike starts and runs, but I think the new battery is firing the coils. I have the rear engine cover removed and I am ready to replace the stator. Can anybody recommend a reliable parts supplier who will sell the stator that fits this bike?
Background: my battery charger has an alternator check feature which indicates the alternator is bad. After riding a few miles, the battery is sufficiently discharged that it does not have enough charge left to start the engine.

 

[Randall-in-Mpls]

The ignition windings in your stator are firing the coils. Unfortunately, you'll need to replace that functionality along with the charging part.
You have a couple options. You can replace it with the same so-called "G47" stator for any CDI-fired CX500 (through 1981.) That's an expensive part.
You can install a charging-only "G8" stator for a GL500 or '82 CX500C. This costs less, but requires an aftermarket replacement of the CDI unit to use ignition power from the battery. This is a more robust system, so it might be the better long term solution.
CDI replacements can be either the Ignitech out of Czech Republic, or the Rae-san unit out of Australia. Ray is a member here and offers excellent support. I don't have direct experience to recommend it.
I've run an Ignitech unit for about a decade and am very satisfied with it. I've only dealt with one failure (on a local member's bike), but I don't know the circumstances that might have contributed to that.
While it's open, get a good look at the camchain, and replace it if it doesn't show a good amount of life remaining.
Expect to replace the mechanical seal in the water pump.
It's a good idea to replace the springs in the starter clutch with Honda OEM.
Replace all the o-rings that are exposed in opening the case.

 

[Randall-in-Mpls]

Let's back up a step. Have you performed the normal resistance tests to determine that the stator is faulty? It is the likely culprit, but the rectifier/ regulator plays a crucial role, too.
You can get similar symptoms from a poor main ground connection.

 

[THX1138]

Yep, you definitely want to do this test first.

 

[Sidecar Bob]

You can also have similar results if the connector between the regulator/rectifier and the stator (3 yellow wires) is corroded or loose.